This present invention relates to an imaging device for forming a visible image on a developing sheet based upon a latent image having been previously formed on a surface of a recording sheet in accordance with an image of an original, more particularly to an imaging device utilizing a plurality of driving system for feeding the above sheets.
Conventionally, an imaging device in which an optical image is formed on a photo sensitive recording medium in accordance with specific image information, for example an image on an original, has been known. Most of this type imaging device have been structured in a manner that a light is radiated from a light source to an original, and the light reflected at a surface of the original is focused on the photo sensitive recording medium through a plurality of reflecting mirrors, filters, lenses, and so forth, and then a latent image or a visible image is exposed on the photo sensitive recording medium.
Especially, this type of imaging device mostly employs a lengthwise sheet wound to a roll as the photo sensitive recording medium. In this type of imaging device, a plurality of drive systems for feeding the photo sensitive recording medium have been used.
Especially, a device disclosed in the specification of U.S. Pat. No. 4,742,374, a lengthwise photo and pressure sensitive sheet and a cut sheet type color development sheet are employed as the photo sensitive recording medium. The lengthwise photo and pressure sensitive sheet is driven to be fed through a plurality of drive systems. A latent image corresponding to an image of an original is exposed on an exposure side of the photo and pressure sensitive sheet on which a plurality of microcapsules, each containing a component to change the rupture strength thereof when exposed, are coated and a mechanical strength of the microcapsules coated on a portion corresponding tot he original image is changed by the light. The color development sheet, on which a developer material reactable with an another component included in the microcapsules to develop a visible image is coated, and the photo and pressure sensitive sheet which are synchronously fed are pressurized with each other, and the latent image is transferred to the surface of the color development sheet, thereby forming a desired visible image on the color development sheet.
To form a beautiful visible image using such an imaging device, it is necessary to precisely feed the photo sensitive recording medium using a plurality of drive systems without a partial deviation. Especially, in a device in which feeds the two types of recording sheets, i.e., the photo and pressure sensitive sheet and the color development sheet, it is necessary to minimize a cumulative feeding error being cumulated during a feeding operation by a plurality of drive systems.
However, using a plurality of drive systems, a small speed variation which occurs when or after an operation at each of drive systems provided along a feeding path of the photo sensitive recording medium are gradually cumulated, though a deviation at each of the drive systems is respectively small. Thus, the whole moving error of the recording medium is increased.
Especially, in a device using two types of recording sheets, i.e., photo and pressure sensitive sheet and a color development sheet, a deviation in each drive system necessarily occurs. Thus, when the above cumulative feeding error increases, a good visible image cannot be obtained.